No study has evaluated the utility of different classifications of chronic obstructive pulmonary disease (COPD) airflow limitation (AFL) in terms of the refined “ABCD” classification of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) or in terms of the impacts on quality of life. This study aimed to compare some relevant health outcomes (i.e., GOLD classification and quality-of-life scores) between COPD patients having “light” and “severe” AFL according to five COPD AFL classifications. It was a cross-sectional prospective study including 55 stable COPD male patients. The COPD assessment test (CAT), the VQ11 quality-of-life questionnaire, a spirometry, and a bronchodilator test were performed. The patients were divided into GOLD “A/B” and “C/D.” The following five classifications of AFL severity, based on different post-bronchodilator forced expiratory volume in 1 s (FEV1) expressions, were applied: FEV1%pred: “light” (≥50), “severe” (<50); FEV1z-score: “light” (≥−3), “severe” (<−3); FEV1/height2: “light” (≥0.40), “severe” (<0.40); FEV1/height3: “light” (≥0.29), “severe” (<0.29); and FEV1Quotient: “light” (≥2.50), “severe” (<2.50). The percentages of the patients with “severe” AFL were significantly influenced by the applied classification of the AFL severity (89.1 [FEV1z-score], 63.6 [FEV1%pred], 41.8 [FEV1/height3], 40.0 [FEV1Quotient], and 25.4 [FEV1/height2]; Cochrane test = 91.49, df = 4). The CAT and VQ11 scores were significantly different between the patients having “light” and “severe” AFL. In GOLD “C/D” patients, only the FEV1Quotient was able to distinguish between the two AFL severities. To conclude, the five classifications of COPD AFL were not similar when compared with regard to some relevant health outcomes.
Classification of Chronic Obstructive Pulmonary Disease (COPD) Using Regression with Gabor Filtration and Random Forest Classification